The present invention relates generally to power conversion systems and in particular to systems and method for reducing the common mode voltage of power conversion systems.
In various applications, such as in aircraft and aerospace, power from an electric generator needs to be converted from one form to another before it is consumed by various types of loads. For example, electric generators typically generate alternating current (AC) power that must be converted to direct current (DC) power. The DC power is then converted back into AC power at a desired frequency and amplitude. A variety of power conversion devices (e.g., rectifier, auto-transformer, etc.) may be used to convert AC power to DC power. Likewise, a variety of power conversion devices (e.g., inverter) may be used to convert DC power to AC power.
A common problem with all types of power conversion systems is the generation of common-mode voltages in the output of the AC-to-DC and DC-to-AC converters. In some cases, the common-mode voltage is sufficient to cause large ground currents that can damage or otherwise shorten the life of the system (e.g., large ground currents generated as a result of common-mode voltages can damage bearings within a load). Common-mode voltages are also a source of electromagnetic interference that can reduce the reliability of a power conversion system and other electronic equipment. A system that reduces or eliminates the presence of common-mode voltages would therefore be advantageous.